Polyurethane Decomposition Using Aqueous Urea Under Overpressure
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Solution Overview
Problem
Existing methods for decomposing polyurethane waste products require the use of hydrocarbon-based diols, which have adverse environmental impacts, necessitating the development of alternative, less harmful substances for the decomposition process.
Innovation Solution
A method involving heating polyurethane-containing material at temperatures between 190° C. to 250° C. under overpressure with an aqueous urea solution containing 1 to 45% urea, allowing partial or complete conversion of polyurethane into a liquid process medium, facilitating easier management and potential reuse of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrocarbon-based diols are used to dissolve polyurethane waste products, then the decomposition process can be achieved, but environmental harm increases
Solution Approach 1:
The invention changes the chemical composition parameters of the decomposition medium by replacing hydrocarbon-based diols with an aqueous solution containing urea and at least one alcohol. This substitution fundamentally alters the chemical basis of the decomposition process while maintaining its effectiveness, thereby reducing environmental harm associated with hydrocarbon substances
Solution Approach 2:
The invention introduces an intermediary substance system (aqueous urea solution with alcohol) that mediates the decomposition of polyurethane. The urea and alcohol act as intermediate agents that facilitate the breakdown of polyurethane bonds without requiring harmful hydrocarbon diols, thus achieving the decomposition goal while minimizing environmental impact
2Ease of operation
If polyurethane is heated to high temperature under overpressure with aqueous urea solution, then polyurethane converts to liquid process medium, but energy consumption increases
Solution Approach 1:
The invention utilizes phase transition principles by heating polyurethane to high temperature under overpressure, causing it to transition from solid form to liquid process medium. This controlled phase change enables the polyurethane to become more manageable and processable, allowing for easier separation and recovery of valuable materials despite the energy input required
Solution Approach 2:
The decomposition process operates under periodic control of temperature and pressure conditions. By maintaining specific temperature ranges (190-250°C) and overpressure conditions for defined periods, the process achieves optimal conversion of polyurethane to liquid form while managing energy consumption through controlled time-temperature-pressure cycles
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively decomposes polyurethane using naturally occurring urea, enabling the conversion of solid polyurethane into a more manageable liquid form, allowing for the recovery and reuse of valuable materials while minimizing environmental harm.
Implementation Method 1
material containing polyurethane is heated to a temperature from 190° C. to 250° C. under overpressure in the presence of an aqueous solution containing 1 to 45 mass percent urea
Implementation Method 2
heating is carried out at a temperature from 190° C. to 250° C. under overpressure
Implementation Method 3
the polyurethane fraction of the polyurethane-containing material, which was originally in solid form has been partially or completely converted into substances in a liquid process medium
Data Source
AI summary
The invention relates to a method for decomposing polyurethane, wherein material containing polyurethane is heated to a temperature from 190° C. to 250° C. under overpressure in the presence of an aqueous solution containing 1 to 45 mass percent urea. It further relates to a liquid process medium obtainable thereby.